Научный периодический журнал «Вестник Южно-Уральского государственного университета. Серия «Машиностроение» основан в 2001 году. Учредителем журнала является Федеральное государственное бюджетное образовательное учреждение высшего профессионального образования «Южно-Уральский государственный университет» (национальный исследовательский университет). В журнале освещаются вопросы развития разных отраслей машиностроения, разработки, создания, внедрения новой техники, новых технологий, новых видов материалов, в том числе композитов, пластмасс, керамики и наноматериалов. Журнал представляет интерес для ученых, работающих в указанных областях, поскольку дает возможность обменяться опытом, а также для аспирантов и студентов технических специальностей вузов. Все статьи проходят рецензирование. Журнал выходит 4 раза в год, прием статей ведется круглогодично, на русском или английском языках. Плата за публикацию составляет 2000 рублей. Журнал зарегистрирован в Федеральной службе по надзору в сфере связи, информационных технологий и массовых коммуникаций (Роскомнадзор), свидетельство о регистрации средства массовой информации: ПИ № ФС 77-57391. Издание зарегистрировано в Международном центре ISSN, номер ISSN 1990-8504 Журнал распространяется по подписке. Каталог «Пресса России», подписной индекс 29211, Интернет-каталог агентства «Книга-Сервис», подписной индекс Е29032. Журнал включен: 1. В Перечень ведущих рецензируемых научных журналов и изданий ВАК по специальностям: 05.02.02 Машиноведение, системы приводов и детали машин 05.02.11 Методы контроля и диагностика 05.05.03 Колесные и гусеничные машины 2.5.3. Трение и износ в машинах 2.5.5. Технология и оборудование механической и физико-технической обработки 2.5.6 Технология машиностроения 2.5.13. Проектирование, конструкция и производство летательных аппаратов 2. В специализированную информационную систему «Российский индекс научного цитирования» (РИНЦ). 3. В Реферативный журнал и Базы данных ВИНИТИ. Редакционная политика журнала основывается на традиционных этических принципах российской научной периодики и строится с учетом этических норм работы редакторов и издателей, закрепленных в Кодексе поведения и руководящих принципах наилучшей практики для редактора журнала (Code of Conduct and Best Practice Guidelines for Journal Editors) и Кодексе поведения для издателя журнала (Code of Conduct for Journal Publishers), разработанных Комитетом по публикационной этике - Committee on Publication Ethics (COPE). В процессе издательской деятельности редколлегия журнала руководствуется международными правилами охраны авторского права, нормами действующего законодательства РФ, международными издательскими стандартами. Редакция просит авторов руководствоваться приведенными ниже правилами и прилагаемыми образцами сопровождающих документов.
Numerical simulation of chip formation during edge cutting machining of 3D orthogonal woven fiber-reinforced composite workpiece. Part 1: A review and models of materials.
Edge cutting machining is more commonly used to produce precise parts made of fiberreinforced composite (FRC) with three-dimensional woven orthogonal structure. The disadvantage of this machining method is increased hairiness of the machined surface, fiber-matrix debonding, peeling and chipping. One possible solution to minimize this disadvantage is to use rational tool parameters and rational tool wedge motion in relation to the axes of the fibers. Such motion can be identified using numerical computer micro modeling of the chip formation process. The difficulty of such modeling it the need to have available both a geometric model of the composite itself and models of composite components, including a model of matrix-fiber boundary layer. Modeling based on the method of smoothed particle hydrodynamics -Smooth Particle Hydrodynamics (SPH) is the most promising type of machining process micro modeling. Currently, no publications, which present SPH micro models of three-dimensional woven composites with the description of matrix-fiber boundary layers, have been found. It was also not possible to find specific models for the matrix-fiber boundary layers. In order to solve the problem of rational machining of FRC workpieces using edge cutting tools, an analysis of published material models and parameters of such models was carried out. These models should be subsequently used for SPH modeling of the machining process. The analysis made it possible to select the required material models and their parameters for fiber and matrix materials of a metal composite. The analysis of the graphical relationships obtained from the publications, made it possible to select the parameters for the fiber-matrix boundary layer model. This selection is based on the hypothesis that the boundary layer should be described by the same model, that is used for the matrix itself, but with parameters that determine lower failure stresses. The obtained solutions are planned to be used to simulate machining process of a workpiece made of three-dimensional woven FRC in the second part of the presented research.
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Review of modern methods for composite materials compacting
The article discusses various methods of compaction of composite materials: static, vibration, shock, as well as combined action. The designs of mechanisms for compaction are given: a vibrating press, a vibrating plate, a mechanism with a ramming bar, a continuous press for molding products from powdery masses with a connecting rod-rocker impact mechanism, a machine for compacting rigid concrete mixtures, and others. Their principle of operation is considered, advantages and disadvantages are indicated. The analysis of existing compacting methods allows synthesizing the accumulated knowledge in this field, combining them into a single system, finding shortcomings and ways to improve the applied compacting methods in order to increase the productivity of the process, reduce the required drive power of the mechanism, improve the operational characteristics of products. The works of Russian researchers are considered: E.A. Shishkin, A.A. Smolyakov, O.G. Klevtsova, V.I. Ivanchura, A.P. Prokopyev and others. The works of foreign researchers are also considered: Donghai Liu, Ning Wang, Erbo Song, Carl Wersall, K. Rainer Massarsch, Johan Spross and others. The research examines modern methods of compaction, including practical experiments aimed at identifying the most optimal parameters of equipment operation and refining the designs of existing mechanisms. The authors note that many processes related to compaction require additional experimental studies, and the existing methods of compaction are not effective enough and have disadvantages that cannot be eliminated without making significant changes. Thus, it is necessary to apply new methods that meet the requirements of modern technological processes.
Development of a vibratory working organ of a subsoiler
The article considers the design of a vibrating working body of a subsoiler, developed for a method of tillage that improves energy and agrotechnical performance. Deep loosening of the soil allows to improve the quality of tillage. Based on the results of the analysis of the working bodies of the tools and methods for reducing the traction resistance of deep diggers (according to the type of working body, the layout of the working bodies on the frame of the tool, the use of vibration of the working bodies), a design solution is proposed that will significantly reduce the traction resistance of the soil to the working body, – the use of vibration in the proposed design using vibrators, which will allow, including It is necessary to reduce energy costs when performing basic tillage. The study of the properties of cultivated soils using vibration made it possible to substantiate, in accordance with the purpose set in the work, a constructive scheme for transmitting vibration to the working body of a tillage. A mathematical model is proposed for determining the traction resistance of a deep loader, which allows calculating the magnitude of the forces acting on the rack of the working body, as well as on a component of its design – a vibrating chisel. The refinement of the traction resistance of the chisel by the resulting centrifugal force of inertia of its rotating element (eccentric) makes it possible to assess the degree of vibration of the working body on the soil. When determining the parameters of the mathematical model, the values of the parameters of the working bodies of deep-diggers and chisels in the conditions of stony soils of the Southern Urals were used. For the calculated scheme of the working body, its design parameters were determined, and a significant decrease in the traction resistance of the chisel gun using a vibrating chisel was obtained. An experimental study of the designed and manufactured prototype of a working organ with a vibrating chisel, conducted in laboratory conditions in accordance with an updated methodology, confirmed the calculated data on reducing traction resistance and improving agrotechnical soil parameters.
Graphical ways to implement the same stroke of pistons of V- and W-shaped engines with trailed connecting rods
This article presents empirical methods of graphical research on the implementation of the same stroke of pistons of V-shaped engines with trailed connecting rods. According to the authors, at a certain stage of research, it is advisable to perform a graphical construction, which could to be more reliable and less costly to use any programs related to determining valid technical and design parameters. Obviously, it is advisable to use two- or three-dimensional modeling based on automatic design systems “Kompas” as a technical tool for achieving the goal. At the first stage, it is enough to design using a two-dimensional modeling system, which allows to asses the ratio of the basic geometric dimensions and possibility of further design. The three-dimensional modeling system allows you to into account the ratio of the parts given their geometric shape and changes in position within the permissible limits of the internal space of CCM and CPG of engine. The peculiarity of graphical research methods involves analysis of the geometric dimensions of the parts and their relative position in a particular engine. In this case, it is advisable to consider the design of CCM of V-shape engines, for example of type V-2, whose peculiarity is to the design of CCM with a trailed connecting rod and to get different stroke of pistons in the main and side cylinders of the engine. In this case, the problem of organizing the identical running of the engine work is connected with the problem of obtaining the same coefficient of excess air, but then the fuel supply to the engine cylinders will be different. The method of shifting the intersection point of the cylinder axes, analyzed in the work, allows the method to be used not only to obtain sufficient space for the pistons at bottom dead center, but also to ensure conditions for the same stroke of the pistons of V- and W-shaped engines.
Features of complex calculation ejection cooling system charge air in diesel
The expediency of increasing the density of fresh charge at the inlet to the cylinder of a diesel engine with a gas turbine boost by using an ejection cooling system after the compressor to circulate cooling air through the cooler is substantiated. The urgency of improving the cooling systems of the charge air is noted in the direction of reducing the cost of power for operation and simplifying the design of their elements. The functional and design features of the elements of the charge air ejection cooling system are considered. The incompleteness of studying the functioning of the ejector at the outlet for intensive circulation of cooling air through the cooler matrix when placing the ejector after the turbocharger turbine is noted. The sequence of calculation of the system in the form of a block diagram is proposed, including a diesel engine, a compressor and a turbocharger turbine, a charge air cooler and an ejector in the exhaust system. The main factors characterizing the relationship between the functional and geometric parameters of the system elements are considered. The features of the complex calculation of the ejection cooling system for charge air in a diesel engine using mathematical modeling of processes in various elements of the system to find reserves and compromise solutions to reduce the cost of power for its operation and increase its efficiency are reflected. The results of the complex calculation of the ejection cooling system of the charge air using numerical modeling are presented graphically in the form of dependences of the parameters of its elements on the degree of pressure reduction in the turbocharger turbine. The analysis of the results of the complex calculation shows that the maximum values of the degree of cooling, charge air density and effective diesel power are achieved at different degrees of pressure reduction in the turbine or ejector. In this regard, it is concluded that it is advisable to choose the required values of the degrees of pressure reduction in the turbine or ejector on a compromise basis when designing an ejection cooling system for charge air.
About one method of ultrasonic well drilling for soil sampling on celestial bodies
The article discusses technical and theoretical issues in the development of an ultrasonic drill for drilling soil on celestial bodies. The specific use of the drill requires low energy consumption, an efficient operating cycle and a wide temperature range during operation. One of the promising areas of development is devices that have vibration decoupling from the ground due to the transformation of ultrasonic vibrations into repeated shocks of sound frequency through a specially introduced “free” body between the ultrasonic and impact parts of the device. This allows you to maintain the functionality of the device and carry out drilling regardless of the state of the impact bit, including even its temporary jamming. The main technical solutions of both domestic and foreign authors are considered, an analysis is made and design schemes, operating conditions, capabilities and limitations are evaluated. A number of theoretical works were also analyzed and it was found that the materials presented in them do not contain detailed mathematical models necessary for simulation modeling at the stage of design and optimization of the structure. The theoretical part of the article considers a lumped mathematical model obtained on the basis of equivalent parameters obtained from a distributed description of the drill design elements in numerical calculation systems. The equations of mathematical physics, classical mechanics, elements of impact theory and similarity theory were used. A parametric study was carried out and, in particular, the dependences of the oscillation frequency of a free body on the size of the impact gap, body mass and the amplitude of oscillations of the concentrator were obtained. The considered model can be used for simulation modeling when developing a drill design.
Prediction of vibration behavior of the case of a promising automatic transmission of a truck based on the method of modal representation of a dynamic system.
This study is one of the stages of research work to create a verified mathematical model of a promising automatic transmission of a truck, which should adequately describe its vibroacoustic behavior during operation. The article presents the results of an experimental study and simulation of the vibration behavior of a promising automatic transmission. The conditions for conducting an experimental study and the results of processing experimental data for 1st gear are given, which make it possible to evaluate the change in the spectrum of characteristic points of the case depending on the rotational frequency, the dynamics of changes in vibration accelerations during acceleration and deceleration, determine the orders of vibration with the largest amplitudes, identify sources of disturbance and justify the need to consider vibrations in a wide range of frequencies for vibration forms of similar frequencies. Based on the simulation results, the vibration forms of the case and the magnitude of vibration accelerations at characteristic points were obtained, verification was carried out and reasonable modifications were made to the mathematical model, and satisfactory accuracy was ensured, allowing us to proceed to the final stage of the study – simulation the acoustic response. Based on the results of the research stage, valuable scientific and technical results were obtained – the order spectra with the largest amplitude were determined – the 45th and 90th order for all gears, with the exception of 6th gear, where the 65th order dominates; sources of disturbance have been identified – engagement of the input shaft gear with the power take-off shaft gear of the oil pump (45th order and multiples of it, up to the 5th harmonic), engagement of the input shaft with the intermediate shaft in 6th gear (65th order), determined the reason for the discrepancy between the results obtained experimentally and by simulation.
Mathematical model of shock-vibration mechanism.
This article considers a mathematical model of the operation of a shock-vibration mechanism for compacting bulk materials (including those that are difficult to deform) based on a four-link mechanism that includes an Archimedes lever. The schematic diagram of the shock-vibration mechanism, the principle of operation and its advantages, relative to similar compaction mechanisms, formulas for calculating the coefficients of increasing the driving force of the drive are given. A mathematical model of the mechanism consisting of geometric, kinematic and dynamic calculations is described. The necessary initial data for the calculation of the mathematical model are highlighted: the dimensions of the links of the mechanism (the radii of the crank and rocker arm, the length of the connecting rod), the masses and moments of inertia of these links, the compaction force. In the geometric calculation, the positions of the links of the mechanism in space are determined depending on the angle of rotation of the crank, the angles of deflection of the rocker arm, the connecting rod relative to the initial position during operation of the mechanism, as well as the positions of the links in space. Kinematic calculation includes the determination of angular velocities and accelerations by differentiating the angles of deviation of the links relative to the initial position, as well as linear velocities and accelerations of the links of the mechanism and at special points. Based on the dynamic calculation, the necessary torque and power are determined, taking into account the force required for pressing, inertial forces and moments, and gravity. During the work, the following operating conditions of the mechanism were highlighted, namely, the maximum lifting angle of the working plate should not exceed 20°, the optimal position of the crank at the end of the working stroke to achieve maximum pressing force, it is necessary to install a flywheel to prevent sudden fluctuations and peak loads.
Increasing the efficiency of an industrial tractor-bulldozer by improving the control algorithm of the motor-transmission unit. Results of mathematical modeling and field tests
The introduction into the design of industrial tractors of continuously variable externally adjustable hydrostatic and electric continuously variable transmissions, as well as internal combustion engines with controlled fuel supply, opens up broad prospects for optimizing the operation of bulldozers and other technological machines based on industrial tractors. Optimization, first of all, in terms of fuel consumption. The materials presented in the article include mathematical modeling of a tractor in the bulldozing technological cycle, formulation of the problem of optimal joint control of the engine and transmission, development of the control algorithm, its implementation in the controller, test conditions and methodology, test results carried out at the plant test site “DST-URAL” in Kalachevo and analysis of the results obtained. As a result, the work carried out by the team of authors recorded a positive effect from the implementation of the developed automatic system, which consisted not only in the expected significant fuel savings, but also in increasing the service life of the internal combustion engine and hydrostatic transmission pumps, and increasing the productivity of the bulldozer, reducing the influence of the human factor (operator qualifications) on tractor performance, increasing operator comfort, reducing cases of activation of the engine overload protection system. Simulation modeling was carried out in the VISSIM programming environment, the code for the controller was created in CoDeSys, testing of the automatic system was implemented on a serial bulldozer tractor produced by the DST-URAL plant D14 with a traction class of 14 tons in August 2023. A patent of the Russian Federation was received for the invention No. 2783552 “Method and device for controlling the motor-transmission unit of an industrial tractor with a continuously variable transmission”. The invention was introduced at the DST-URAL plant.
Development of methods for monitoring of the moment of occurrence of self-oscillation of the cold rolling mill.
In a cold rolling mill, self-oscillations occur when the rolling speed of a thin strip is manually increased. The thickness of the lining is usually no more than 2–2.5 mm. The oscillation spectrum is quite wide. The first harmonic is 120 Hz. During the control of vibration and technological parameters, a rigid relationship was revealed between the vibration of the elements of the mill stands with the vibration displacement of the hydraulic tensioned (GNU) of the working rolls and fluctuations in the tension level of the rolled strip. The regular control of the movement of wildebeest makes 200 measurements per second. In accordance with Kotelnikov's theorem, the frequency band of the spectral characteristic in this case is 100 Hz. Fluctuations in the tension level of the rolled strip allows you to control the frequency band in the range from 0 to 43 Hz, no more. This is clearly not enough to reliably control the moment of occurrence of selfoscillations. The existing control system for technological parameters has an internal resource for the frequency of polling when forming a database. Using software, it was possible to increase the frequency of the survey of vibration displacements of wildebeest to 1000 measurements per second. In this case, the frequency band of the spectral characteristic covers the range from 0 to 500 Hz. This allows you to control not only the first harmonic of 120 Hz, but also the higher harmonics up to 400–500 Hz. Fluctuations in the tension level of the rolled strip after switching to a faster controller resource made it possible to increase the polling frequency to 250 measurements per second. Thus, it is also possible to reliably control the first harmonic of the resulting self-oscillations through this channel. An analysis of the process of self-oscillation has shown that the cause of self-oscillation of the mill stands is a spontaneous fluctuation in the tension level of the rolled strip with a manual increase in the linear rolling speed. The vibrations of the mill stands are delayed relative to the fluctuations in the tension level from 2 to 3 seconds. Using discrete Fourier transform and short-range Fourier transform (STFT) algorithms, it is possible to reliably and timely recognize the moment of occurrence of self-oscillations.
Parameter determination method for twist drill point thinning using “KOMPAS 3D”
Standard twist drills have significant design flaw: chisel edge rake angles have large negative values. Chisel shortening with abrasive tool is commonly used to minimize this disadvantage. The choice of such a tool, tool parameters and parameters of its location relative to the drill affect point thinning measure and rake angles of the thinned cutting edge. Difficulties of abrasive tool selection are related to the presence of drill helical flutes and their intersection with the major flanks. The paper presents a method for determining rational parameters of point thinning based on classical solid modeling using “KOMPAS 3D” software. The method uses the following parameters: abrasive wheel diameter, wheel profile radius, inter-axial distance, distance between the wheel axis and the drill cutting part, angle of crossing of their axes and angle of the wheel base end rotation relative to the base axial plane of the drill. The maximum value of the drill side rake in the considered drill part is taken as the selection criterion. The technique is based on developing a parametric model of standard drills, with automatic model updating according to drill dimensions specified in the standards. The chip flute is modeled using helical movement of the standard milling cutter surface. The technique is developed for industrial plants specialists `who are involved in further tool development for specific production conditions.
Development of a closed-type shot model from composite materials at the South Ural State University.
The task of improving standard shots in terms of stealth, noiselessness and increased power is relevant, since it allows, on the one hand, to increase the combat capabilities of crews on the battlefield, and on the other, to create mock-ups of shots when training students in the specialty 05.17.01 “Ammunition and fuses”, allows you to instill skills and competencies in the development and production of modern weapons and ammunition. The Federal State Autonomous Educational Institution of Higher Education “South Ural State University (National Research University)”, based on accumulated scientific and practical experience, offers for consideration a design model of a closed-type silent shot made of composite materials, the concept of which was developed on the basis of a RU patent 2741982 C1. As part of the educational process in the specialty 17.05.01 “Ammunition and fuses”, a set of design and technological documentation was developed, materials and technological equipment for its production were selected. The design of the model consists of polymer composite elements: head and tail parts. The warhead contains inconspicuous ceramic ready-made submunitions. In the tail section there is a replaceable powder propellant charge. A review of currently used foreign radar stations was carried out. The ballistic and aerodynamic parameters of the developed shot model and the fragmentation efficiency were assessed. The results of modeling the flow of air around and the dispersion of fragments are presented. This sample is an illustration of the scientific and methodological approach to creating designs and technologies for promising samples of weapons and ammunition for the industry of conventional weapons, ammunition and special chemicals of the Russian Federation
Theoretical analysis of the interaction forces of weeds and volatiles upon impact on the grate.
In recent years, a trend has emerged based on the method of imparting mobility (degree of freedom) to the grate. The practical implementation of this method is carried out in two ways: a grate where the grates receive movement under the influence of a technological load, and in the second when the grate is forced. The work theoretically and experimentally investigated the impact interaction of raw cotton with grates. Typically, in grate-serk type cleaners, raw cotton is cleaned by striking clogged flywheels mounted on a serrated set against stationary grates. The article examines the process of impact interaction of a clogged fly with a grate having forced rotation. Formulas have been proposed for determining shock pulses acting on fly and impurities when hitting a grate with forced rotation. This will allow us to find ways to increase the cleaning effect of using a grate with forced rotation in a cotton ginning unit. Formulas have been obtained for determining the shock impulses acting on fly and impurities when hitting a grate with forced rotation. The values of impact forces are determined, calculated depending on the diameter and rotation speed. The cleaning effect of using a grate with forced rotation in a cotton ginning unit is 95.5–97.5 %.
A method for mathematical modeling of the hydrodynamic friction of plunger pairs in terms of microgeometry
The fuel injection system strongly relies on a high pressure fuel pump which is essential for its overall performance. The fuel pump plunger is subject to high loads and irregular lubrication under dynamic loads, which leads to its premature wear. The industrial sector uses laser surface micro-texturing to reduce friction and improve anti-wear properties. Its positive effects are supported by both theoretical and experimental data. The paper presents a method for determining the hydromechanical characteristics of plunger pairs during hydrodynamic friction. The microgeometry of friction surfaces was taken into account due to the lubricating fluid cavitation effect described by the modified Reynolds equation. The proposed method can be applied to develop the software to analyze the contacting surfaces of plunger pairs and evaluate their tribological characteristics based on the microgeometry parameters of friction surfaces. The paper also studies the influence of microgeometry parameters on the quality criteria of the hydromechanical characteristics of plunger pairs. It gives the calculated examples of analyzing the contacting surfaces of plunger pairs separated by a lubricant layer. The technical specifications are assessed depending on the microgeometry parameters of the friction surface roughness.
Experimental study of a vortex-type shut-off device
Modern technologies for obtaining materials include chemical reactions occurring at excess pressure and high temperatures accompanied by phase transitions. Such processes take place in devices for sulfuric acid production, heterogeneous catalysis and chemical synthesis, in devices for drying, burning and melting bulk materials and other furnaces. The technological processes under consideration are accompanied by the loading of bulk material into the internal cavity of the apparatus – the reactor. In this case, the material loading window is sealed by a mechanical locking device which opens at the stage of the technological process, accompanied by loading of raw materials into the reactor. In this case, the air-tightness of the reactor is broken and gases can be released into the environment, which poses a threat to the health of the working staff and the environment as a whole. The article focuses on an experimental study of the gas-dynamic characteristics of the air flow at the exit of the annular nozzle of a vortex-type pneumatic shut-off device. The paper analyzes the methods for studying hydro-gas-dynamic parameters of vortex flows with justification for the choice of the study method. It also describes the laboratory setup and instrumentation for the study. The results of the research include the distribution of total pressure from the axial component of velocity and its structure. We also constructed the diagrams of the distribution of the axial component of the active air velocity and obtained a refined velocity distribution along the nozzle radius. The results of the study indicate the operability of the device and can be used in the physical and mathematical description of the working process of a vortex pneumatic shut-off device, as well as in the development of methods for optimal profiling of the device.
Experimental studies and identifying a model of the dynamic system “anti-vibration seat – operator” of a mobile machine
When creating new types of transport and technological mobile machines, it is important to ensure compliance with sanitary standards for vibrations at the driver’s seat. Anti-vibration seats are widely used to reduce vibrations transmitted from the engine and chassis of the machine to the operator's workplace. When designing a machine, mathematical modeling can be used to make a reasonable choice of seat parameters. Since the anti-vibration seat together with the operator’s body form a single dynamic system, the mathematical model must include both the anti-vibration seat and the operator’s body. The article presents an overview of mathematical models that describe vertical vibrations of the seated body. It describes an experimental setup for studying the dynamics of a human operator sitting in an anti-vibration seat. The experimental setup includes an electrodynamic vibration bench produced by LDS, control and recording equipment. The studies were carried out for the Sibeco anti-vibration seat. During testing, the base of the seat performed vertical harmonic vibrations with a gradually increasing frequency, while the amplitude of vibration accelerations was maintained constant. The accelerometers installed on the seat elements, on a special disk located on the seat cushion and on the operator’s body, recorded vibrations of these elements. As a result of processing experimental data, transfer functions were obtained. They connect the amplitudes of movement of various elements of the model with movements of the base in a given frequency range. The experiments were carried out with the participation of testers with different body weights. The article proposes a mathematical model that describes the vertical vibrations of the “vibrationprotective seat – operator’s body” system. The inertial and elastic-damping characteristics of the seat elements were determined earlier during special tests. Based on a comparison of calculated and experimental data, the parameters of the model elements describing the operator’s body were refined. The parameters of the mathematical model obtained during the study will be used in the future research for calculation estimates of the vibration load of the operator’s workplace.
Influence of the speed of stretching the rolled strip on the occurrence of self-oscillations of the tension station of the cold rolling mill 2000.
The self-oscillations of the roller of the tension station of the loop accumulator of the cold rolling mill lead to the appearance of cracks on the outer surfaces of the roller during operation. In order to determine the causes of self-oscillations of the crack, we conducted a screening industrial experiment to assess the influence of technological and diagnostic parameters on the state of the tension station of the etching unit of mill 2000. The database of technological and vibration parameters of the mill and the roller of the tension station is a single hybrid database combined with a graphical shell. An industrial experiment is, as a rule, a passive experiment. It is an experiment in which the experimenter does not have the opportunity to interfere in the process of conducting the experiment. But in the case of a cold rolling mill, one single independent experiment requires only 5–6 minutes. Each roll is of different thickness, width, different chemical composition and, accordingly, with different mechanical properties. In addition, the rolling speed, strip tension, strip compression, different friction forces at the tension station are different. Each roll is an independent experiment. If information about technological and diagnostic parameters is stored for a long time, for example, a year or two, this information is enough to work with it as with a laboratory experiment. With a time lag, but with enough information to plan the experiment. It is only necessary to select information from the data array that corresponds to the experiment plan. Using a database a Digital Twin, we carried out an industrial experiment to determine the conditions for the occurrence of self-oscillations of the roller of the tension station and the rolled strip. The results obtained revealed a clear dependence of the occurrence of HC8 self-oscillations on the speed of stretching the strip at the time of cutting out a non-metallic inclusion (Class 3). The stretching speed should be in the range from 0.5 to 1.0 m/s. At stretching speeds in the range from 2.0 to 2.5 m/s, self-oscillations do not occur. There are no conditions for the occurrence of cracks on the end surfaces of the roller.
Design of flexible hole milling cycles on CNC machines
The paper describes the stages of designing the technological end hole milling cycle and presents the developed CONICALINT software, which generates a G-code with argument lists used to call up a technological cycle from the CNC system memory. The developed algorithm for the technological end hole milling cycle has a branched structure, since it can choose between two methods for calculating the internal cycle parameters and two milling methods – climb down and climb up. The calculation of the internal technological cycle parameters consists of calculating the coordinates of the points necessary to construct the helical path of the cutting tool, as well as the maximum permissible value of the helical pitch within a given set of input parameters. The initial calculation data are represented by thirteen parameters characterizing the geometry of the cutting tool, the geometry of the required machined surface, as well as the parameters that determine the milling method and the method for calculating the cutting mode and the starting points of the cutting tool path. We identified eight boundary conditions that determine the permissible values of the input parameters. Based on these conditions, we designed a system of inequalities with a set of error messages displayed to the user if any of the input parameters is entered incorrectly. The developed Gcode of the technological cycle subprogram for a CNC machine calculates the tool movement both along a helical and a conical helical path, depending on the input parameters, which allows using it to program cylindrical and conical hole milling. The developed CONICALINT software is a visual addition to the developed technological cycle of hole milling. The developed CONICALINT software is a visual addition to the developed technological hole milling cycle, which allows generating a control G-code with a set of twelve arguments.
Mathematical substantiation of the limit value of tagential traction force on driving wheels for transport-technological machines.
The paper deals with the aspects of determining the ultimate traction force on the driving wheels of land transport and technological machines (LTTM) with 4×2 wheel arrangement. The purpose of the study was to identify the criteria that limit the maximum value of traction force on the driving wheels that can be realized on machines of this type. These criteria are determined by the torque generated by the engine and transformed by the transmission, and are grouped into the following groups: those related to the onset of slipping of the driving wheels and those determining the overturning of the NTTM and the limiting moments for the destruction of the transmission elements. The article presents mathematical dependencies developed to determine the limit values of traction force on the wheels of NTTM. The authors have developed a model that allows conducting numerical experiments to determine the optimal parameters of the engine and transmission. This allows determining the limit thrust force which can be operated with in the further development of the project. These dependencies allow taking into account the influence of various factors in the traction balance equation. The factors affecting the realization of torque are the mass of the machine, including the distribution of mass on the axles and the relative position of the center of mass, the friction coefficient, the angle of inclination of the road and other parameters of interaction with the supporting surface, as well as the characteristics of the transmission that limit the traction capabilities of the machine. After transforming the obtained mathematical expressions, the authors describe the dependence that determines the maximum allowable torque on the crankshaft of the engine. It allows taking into account the engine characteristics when determining the limiting force of traction and provides the possibility of choosing the engine power characteristics for a particular transport-technological machine and transmission ratios.
Assessing the technical possibility of achieving the same piston stroke in a crank mechanism with trailed connecting rods.
The article presents the technical capabilities for achieving the specified operating characteristics of engine components and parts taking into account the geometric characteristics of the crank mechanism (crank mechanism). It also presents the assessment and achievements of the required level of strength parameters of some structural elements of the main connecting rod and the entire mechanism as a whole. Making changes to a proven design and established production is a complex and multifactorial task. It is necessary to make changes that would minimize production and technological losses. Besides, they must fit harmoniously into existing technology and production capabilities ensuring the fulfillment of new technical requirements and characteristics. When solving the problem of ensuring the same piston stroke for a V-2 engine, the analysis of the design documentation showed that in addition to making changes to the design of the crank mechanism, it is necessary to make changes to other engine parts. The need for these changes was determined by the method of “scrolling” the assembly of crankshaft parts in the volume of the engine crankcase using 3D modeling programs for parts and checking their performance. The results of assessing the kinematics of the crankshaft engine of V-2 type engines proved that in addition to changing the design of the main connecting rod, it is necessary to perform additional processing of the axial stiffener rib of the upper half of the crankcase, as well as to make changes to the design of the trailing connecting rod in order to eliminate contact with the cylinder liner and, possibly, the liner itself. However, changes in the engine design will entail significant changes in the technological process of its manufacture. Obviously, these changes should be minimal. In order to preserve the engine design, it is necessary to make some significant changes. They can affect significant production and technological changes, which in conditions of mass production require fairly strong theoretical and practical justification. Therefore, when implementing these technical solutions, it was necessary to perform calculation and kinematic analysis based on 3D modeling and logical analysis, excluding disruption of engine operation. In addition, to assess the load on the lower head of the connecting rod, a hydrodynamic calculation was performed. The results also include the hydromechanical characteristics of a complexly loaded bearing and a diagram of the hydrodynamic pressures acting in a thin lubricant layer.
Theoretical aspects and problems of calculating short-circuit currents power supply systems or the traction electric drive of an active semi-trailer
The article describes and analyzes theoretical aspects and problems arising from the calculation of short-circuit currents of the power supply system of the traction electric drive of alternating current. The power system includes a semiconductor rectifier and a traction inverter. The electric drive is located on the chassis of a semi-trailer, an active semi-trailer, which is part of the “Arctic road train”. The above issues have been worked out, but, nevertheless, the conclusions require clarification through additional experimental verification. The active semi-trailer is designed to transport a multifunctional module for medical and household purposes at ambient temperatures from minus 50 to plus 40 ° C on paved roads, on dirt roads of various conditions, on terrain with soils with weak bearing capacity and virgin snow. The traction electric drive as part of an active semi-trailer is designed to create additional traction forces in difficult vehicle driving conditions in order to overcome obstacles, off-road and hills. This semi-trailer is being created as part of a project to develop a unified family of vehicles “Arctic Bus” and “Arctic Road Train with a Transportable Functional Module” to organize the safe transportation of passengers and mobile social points in the Far North at low temperatures (up to minus 50 °C) and to ensure the connectivity of the territories of the Arctic zone of the Russian Federation. In this regard, traditional methods for calculating short-circuit currents, as well as typical principles for choosing protection devices, checking their settings, fuse settings, resistance of cable lines and buses to short-circuit currents cannot be applied to the power supply system of the traction electric drive of an active semi-trailer, which determines the relevance and necessity of further research in this area. This article proposes calculations which can be used in the development of a methodology for calculating short-circuit currents of the power supply system of a traction electric drive using reversible and irreversible semiconductor converters with a direct current link.
Experimental study of gasdynamic bearing operability. Cracking of the roller of the tension station of the loop accumulator of the tandem cold rolling mill 2000.
The question of the high-speed turbo machines operability is directly related to the processes occurring in the support structures – gas sliding bearings. The most common structure of such supports is the multi-petal bearing. One of the main research directions in this area is the development of a design ensuring the reliable operation of the bearing. The durability of gas bearings depends directly on the number of start-stop cycles, which is its key difference from liquid bearings. The start-up period of the turbo machine represents the most challenging mode of operation for the petal gas dynamic bearings. A critical feature of this mode is the insufficient formation of a gas layer at low rotational speeds. The load on the working surfaces of the support is assessed as nominal, equal to the rotor's weight. If the start-up mode of the turbo machine is successfully passed, then in future, during the acceleration, it will be operational. The research of the transitional mode during the start-up requires a complex approach, including both theoretical and experimental studies. This paper is a continuation of theoretical studies for multi-petal gas dynamic bearings with overlapping petals. The key parameters ensuring the operability of such supports include the shaft ascent speed at the start-up and the value of the force acting on the support. As part of the research, an experimental installation was developed to obtain values of shaft ascent speed depending on static load force. Series of experiments included different variations of initial loads, up to the critical value. The results of the experiments provide the values of permissible static loads and a range of shaft ascent speed values. This study facilitates further parametric investigations in the mathematical modeling of processes occurring in gas dynamic bearings.
Cracking of the roller of the tension station of the loop accumulator of the tandem cold rolling mill 2000.
In the event of self-oscillation of the roller of the tension station of the loop accumulator of the cold rolling mill, cracks appear on the outer surfaces of the roller during operation. Determining the causes of cracking and assessing the residual life of the roller of the tension station is an urgent task. A digital double of the tension station of the loop accumulator of the cold rolling mill has been developed in accordance with the classification of Michael Reeves and in accordance with the standard GOST R 57700.37-2021 “Computer models and modeling. Digital doubles of products”. The technological parameters and diagnostic data used, reflected and stored in an environment external to the industrial facility, represent a “digital shadow”. Databases of technological and vibration parameters of the mill and the roller of the tension station are combined by a graphical shell. A numerical 3-dimensional model of a tensioning station roller is constructed. The eigenforms and eigenfrequencies of the oscillations are determined. The lower eigenforms obtained by calculation are consistent with the vibration frequencies of the bearing supports of the tensioning roller stored in the digital footprint of the mill. At high frequencies, a mixed form of oscillations is observed (shell oscillations, and bending of the semi-axes) which also has an approximate match on the vibrograms of the digital footprint. Vibration acceleration and loading cycles of the bearing supports of the tension station are associated with the use of a virtual industrial experiment. The numerical 3- dimensional model of the tensioning station roller determines the real loads acting on the end surfaces of the roller when self-oscillations of the tensioning station occur. Information about the frequency and amplitude of vibrations allows you to calculate the number of loading cycles and estimate the residual resource before cracks occur on the end surfaces of the roller of the tension station.
Wavelet transformations in monitoring and diagnostics of self-oscillations of a cold rolling mill.
Self-excited oscillations remain a frequent problem of cold rolling of thin strips. When self-oscillations occur, the amplitude increases by a jump of more than a hundred times, that is from 2–3 m/s2 to 200–250 m/s2. Oscillation frequencies (from 100 to 500 Hz, i.e. the number of loading cycles) can reach several thousands per a few seconds. Intense self-oscillations normally occur on thin strips with a thickness of less than 1 mm and high rolling speeds. The control of the occurrence of self-oscillations includes special systems, according to the level of vibrations or technological parameters, for example, by fluctuations in the tension of the strip. In control systems, classical methods include the decomposition of the controlled signal into a Fourier series. For stationary processes, Fourier series decomposition provides complete information about the signal structure and is sufficient to diagnose the technical condition of machines and mechanisms. As for a nonstationary non-harmonic signal, the information about the spectral composition of the diagnostic signal is insufficient, since it does not allow for determining the moment of occurrence of an undesirable process. In metallurgy and rolling production, processes are frequently not stationary. The cold rolling process is continuous, but discrete. It takes 5–6 minutes to roll one coil. The process of selfoscillation, even when using control systems, can last no more than 2–3 seconds. A high frequency of vibrations and a high level of stress can lead to the formation of cracks in the elements of the mill stands, for example, CVC plates. A signal conversion wavelet can become an alternative way of monitoring and diagnostics. If the FFT allows you to determine the presence of self-oscillations only in the developed state, the wavelet transform allows you to determine the origin of the selfoscillation process at low oscillation amplitudes. It also allows you to determine it in the absence of fluctuations by changing the signal of the technological parameters.
The role of geocosmic transport in the large-scale industrialization of the space
Today, humanity is faced with a number of environmental problems, the solution of which depends on our continued existence. The authors propose a systematic approach to get out of this situation, which is described in detail in the EcoSpace program. The main vector of further industrial development will be space, but its implementation requires transport that has a number of unique characteristics. The authors of the article proposed the design of a general planetary vehicle (GPV), which is a self-supporting aircraft (with a length of 40,076 km, a total mass without payload of about 30 million tons), made in the form of a torus with a cross section of several meters, covering the planet in a plane, parallel to the equator. A solution to the problem of stabilization of the central position of the rotor in the channel of the stator of a general planetary vehicle (GPV) with the help of the forces of the magnetic fields of permanent magnets is proposed. The designed system compensates for external forces acting both on the rotor during takeoff preparation and on the stator during climb. The diagrams of the distribution of magnetic fluxes in the suspension, as well as under the influence of the Earth's gravity force on the rotor near its surface, are given. Thus, a general planetary vehicle, designed to move all harmful industrial production beyond the planet Earth, opens up prospects for using the conditions of weightlessness, vacuum, ultra-low and ultra-high temperatures, spatial, energy and raw materials of near space and the boundless Universe. The results of the conducted studies and their analysis demonstrate that UTS is able to provide a planetary scale and a rapid pace of practical implementation of the uSpace project.
Caterpillar drive elements interaction when the first roller wheel hits an unevenness process dynamic.
The article focuses on the dynamics of high-speed tracked vehicle caterpillar drive elements and their interaction when moving over unevenness. Such movements are accompanied by the previously insufficiently studied effect of the caterpillar drive free branch capturing by the drive wheel gear rim in its front location, which leads to the destruction of the structural elements of the power unit. The paper presents the results of dynamic wave processes in a caterpillar drive obtained using mathematical modeling. The model, in which the dynamic system is presented as an elastic rod on an inertialess elastic foundation, takes into account the inertial dynamic loads in the caterpillar drive formed by the soil microprofile. It also allows us to analyze with satisfactory accuracy the dynamic excitation process of transverse vibrations in a free branch. The computational and experimental results of studying the dynamic process of free-branch transverse wave oscillations (when the first roller wheel hits an unevenness) demonstrate that due to the significant inertial force influence, the caterpillar oscillations amplitude increases significantly, which increases the likelihood of its capture by the drive wheel gear rim. The free branch transverse oscillations amplitude does not significantly depend on the design parameters. The determining factor is the pretensioning force. When the first track roller hits an unevenness, it is not a controllable value and, in the limiting case, can be reduced to zero. To reduce the likelihood of the drive wheel being caught by the gear rim, it is necessary to introduce an additional track tensioning mechanism and an appropriate control system into the design of the caterpillar mover with the front location of the drive wheels.
ossibilities for improving the systems for accounting the technical and economic indicators of mining enterprises using equipment reliability calculations (on the example of dump trucks of the Chernogorskiy mine)
At present, the use of standard technical and economic indicators of a mining enterprise to account for the operation and repair of BelAZ heavy-duty mining dump trucks does not provide a complete understanding of the reasons for the failure of these machines and all mining equipment. This makes it difficult to determine the initial causes of failures and the conditions for their occurrence, which in turn hinders the development of more effective maintenance and repair strategies for BelAZ dump trucks. To solve this problem, it is necessary to use formulas for calculating reliability indicators, such as the Stegers formula and the mathematical expectation of time to failure. To solve this problem, it is necessary to use formulas for calculating reliability indicators, such as the Stegers formula and the mathematical expectation of time to failure. These methods allow you to more accurately determine the likelihood of failures and identify the most likely causes of its occurrence. Thus, they contribute to a more effective management of the risks of equipment failure and increase the reliability of the system for the use of BelAZ heavy mining dump trucks and their repair. However, the use of formulas for calculating reliability indicators requires a higher qualification of employees of a mining enterprise, additional knowledge and skills in the field of mechanical engineering, mathematics and statistics. In general, the use of technical and economic indicators in combination with formulas for calculating reliability indicators is an important tool for improving the efficiency and reliability of the system for using BelAZ dump trucks and their repair at a mining enterprise. However, in order to achieve maximum efficiency of equipment operation, it is necessary to take into account all possible factors that affect the process of operation and repair of BelAZ heavy-duty mining dump trucks, as well as constantly improve risk management methods and tools.
FORMATION OF THE APPEARANCE OF A PROMISING BASIC CHASSIS FOR MOBILE FIREFIGHTING EQUIPMENT IN THE ARCTIC ZONES OF THE RUSSIAN FEDERATION
The paper proposes the design of a promising platform as a base chassis (BC) for mobile firefighting equipment in the Arctic zones of the Russian Federation. The methodology is based on a system analysis. It included the analysis of climatic and soil conditions in the Arctic zones of the Russian Federation. The creation of such special platforms as basic chassis for the placement of fire extinguishing means is highly relevant. The study demonstrates the main ways and defines the methods of creating new and improving existing basic chassis of special equipment in order to prevent the occurrence and elimination of the consequences of emergency situations. It analyses the structure of existing and prospective BC and identifies the main structural units as the main parameter when creating new and improving existing BC. The paper considers the effectiveness of the BC as a component element of the effectiveness of mobile fire extinguishing means. It also determines the main indicators characterizing the efficiency of the BC and proposes the concept of an articulated multi-component BC. It highlights the main features characterizing the articulated BC as promising for use in extreme climatic conditions of the Arctic zones of the Russian Federation. The signs include multi-sectionality, a single energy module, adaptive distribution of power flows between sections, quick-release connections between sections. The formation of a transport train according to the number and composition of sections is based on the type, remoteness of the emergency center, weather conditions and terrain at the location of the center and on the way to it.
METHODOLOGICAL ASPECTS OF THE NUMERICAL STRENGTH ANALYSIS OF THE POWER FRAME OF AN ATV
The design of an ATV structure is a complex engineering task, where the development of a load-bearing frame is one of the priorities, which requires a systematic methodology. Purely analytical approaches to calculations, the results of which can be used in the development of a threedimensional tubular frame structure, are now becoming a thing of the past, since the assumptions used in analytical methods give a significant calculation error, which makes it possible to obtain only a very approximate picture of the distribution of stresses and resulting deformations of the structure. It is also necessary to take into account that modern design technologies provide for the simultaneous use of various profiles of not only round, but also more complex sections, which should provide the necessary functionality of different sections of the frame (while providing a sufficiently large number of structural requirements for it), but significantly complicates the calculation procedures. With such input data, preliminary virtual electronic simulation of real products in combination with subsequent numerical engineering analysis is optimal and allows taking into account various design and technological nuances. Such software systems as CATIA related to PLM-systems (PLM – English product lifecycle management system) make it possible to perform both product modeling and, in fact, a series of numerical experiments within a single interactive environment. In the conditions of real design at the production facilities, such works are methodologically undeveloped and innovative. The purpose of the article is to consider approaches to optimizing the design of the power frame of an ATV using software computer engineering analysis tools and a previously created electronic geometric model of an ATV. In particular, the issues of preparing a model for subsequent finite element partitioning, evaluating the results of a numerical study in relation to evaluating the performance of the designed power frame of an ATV under the conditions of using the component base of previously developed power frames of motorcycles and buggies are touched upon.
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SELF-OSCILLATION OF THE TENSION STATIONS OF AN ETCHING UNIT COMBINED WITH THE TANDEM COLD-ROLLING MILL 2000
On multi-cage cold rolling mills combined with a continuous etching unit, self-oscillations can occur not only on the mill stands but also on the tensioning stations of the etching unit. Fatigue cracks can appear on the rollers of the tension stations, and characteristic defects can appear on the surface of the polyurethane-coated roller. To measure self-oscillations, MEMS accelerometers are installed on the roller bearing supports. The collection of vibrational data takes place in parallel with the measurement of technological parameters. Time series databases are used for data storage. The hybrid database allows the simultaneous processing of technological and vibrational parameters. When an emergency situation occurs, it is possible to chart the dependence of self-oscillations on the technological parameters. Using the results of an industrial experiment, it was possible to obtain the characteristic of the friction of the rolled strip on the roller of the tension station at low strip movement speeds. At band speeds from 0.5 m/s to 1 m/s, the friction characteristic is in a transient mode and can be either positive or negative. With a negative characteristic of friction, self-oscillation appears, with a positive characteristic, the movement of the belt stabilizes. Signal processing was carried out using Fast Fourier Transform (FFT). According to the spectral characteristic, it is possible to determine the number of complete cycles acting on the oscillatory system. Having a sufficient amount of information in time, it is possible to calculate the number of cycles and estimate the residual resource before cracks appear on the end surfaces of the roller of the tensioning station.